The invention relates to a sensor module having a housing with a cover that can be fitted on a wall. A pressure sensor is disposed in the housing and a sealing cushion seals the housing interior from the environment. The sealing cushion contains a through-passage channel that connects a pressure-sensitive sensor surface to the environment.
A sensor module of the generic type is known from Published, Non-Prosecuted German Patent Application DE 197 37 821 A1. Provided in a water-tight housing is a sensor element which is embedded in a protective device, for example an elastomer compound, and can be subjected to the action of the atmosphere or of pressurized surroundings via a through-passage channel. The channel leads from a pressure-sensitive surface or diaphragm of the sensor element to a connecting branch, which can latch into a sealing element that is located in a housing or a wall. The pressure-sensitive surface of the sensor may thus be subjected to ambient-pressure fluctuations without the pressure sensor being exposed to ambient humidity.
A sensor module is also known from Published, Non-Prosecuted German Patent Application DE 44 47 513 A1. The housing of the sensor module is a water-tight housing and has a top part and a bottom part as well as a seal disposed between the top part and the bottom part. With the housing assembled, a printed circuit board, on which the pressure sensor is disposed, is accommodated between the top part and the bottom part. The pressure sensor is enclosed by a sealing cushion which, with the housing assembled, is pressed against the printed circuit board by the top part and seals the interior of the housing in relation to a through-passage channel which is formed by a connecting branch, which is formed integrally with the top part and through which the pressure-sensitive surface of the pressure sensor can be subjected to ambient-pressure fluctuation. In order to seal the pressure sensor in relation to moisture from the surroundings, the sealing cushion enclosing the pressure sensor is provided with a diaphragm.
The known sensor module is attached, for example, in vehicle side doors for impact detection. In this case, for reasons of functional reliability, absolute water-tightness is necessary since water and dirt penetrate into the door cavity disposed beneath the windows.
It is accordingly an object of the invention to provide a sensor module having a housing which can be fitted on a wall which overcomes the above-mentioned disadvantages of the prior art devices of this general type, such that the requirements to be met by the housing in terms of water-tightness and sealing against dirt are reduced, but that the sensor module can nevertheless sense certain parameters in a space exposed to moisture, dirt or other rough ambient conditions.
With the foregoing and other objects in view there is provided, in accordance with the invention, a sensor module to be fitted on a wall having an opening formed therein. The sensor module contains a housing to be disposed in the wall and has a housing interior. A cover is attached to the housing and a pressure sensor is disposed in the housing and has a pressure-sensitive sensor surface. A sealing cushion is provided for sealing the housing interior from the environment. The sealing cushion has a through-passage channel formed therein connecting the pressure-sensitive sensor surface to the environment. A connecting branch connects the through-passage channel to the environment through the opening of the wall. The connecting branch has an end butting with sealing action against the sealing cushion, and the sealing cushion is clamped inbetween the connecting branch and the pressure sensor and presses with sealing action against the pressure sensor.
It is possible for the sensor module according to the invention to be disposed on one side of a wall that separates, for example, a wet space from a dry space, and for the parameter that is to be sensed by the sensor module to be sensed through the wall. It is ensured that the housing interior, which accommodates for example electronic circuits and the like, is protected against being influenced by the harmful ambient conditions on the other side of the wall. The sensor element may be suitable, for example, for sensing temperatures, humidity, pressure fluctuations, etc.
The sensor module for sensing pressure fluctuations according to the invention may advantageously be used, for example, in vehicle side doors that are provided with a partition wall that runs in the longitudinal direction of the vehicle and subdivides the side door into two spaces. Disposed in a dry space is all the electronic equipment that is to be disposed in the vehicle door, for example window motors, locking electronics, etc. The dry space is separated off, by the partition wall, from the wet space on the outer side of the door, into which moisture, dirt, etc. penetrates. In the case of the sensor module according to the invention, the housing may be disposed on the partition wall within the dry space. Nevertheless, it is possible to sense the pressure prevailing in the wet space of the vehicle door, which is absolutely necessary if side impact is to be inferred from pressure fluctuations emanating from the outer door panel. In this way, the sensor module according to the invention may be configured with a housing in which the requirements to be met by the sealing are reduced and which is thus cost-effective to produce.
In accordance with an added feature of the invention, a sealing body is attached to the connecting branch such that, with the sensor module fitted on the wall, the sealing body is disposed between an outside of the connecting branch and the opening in the wall.
In accordance with an additional feature of the invention, the connecting branch is guided through the cover, and the connecting branch has an annular flange that butts against an inside of the cover.
In accordance with another feature of the invention, a base plate is disposed in the housing and bears the pressure sensor. The annular flange has a side directed away from the inside of the cover. The annular flange has resilient legs on the side for fitting the connecting branch on the base plate.
In accordance with a further feature of the invention, the connecting branch is guided through the sealing body.
In accordance with another added feature of the invention, the connecting branch is inserted into the sealing body, and the sealing body is configured with an extension extending from the connecting branch.
In accordance with another further feature of the invention, the cover and the connecting branch are formed as a one piece unit. The cover has a run-off nose from which water can drip off, and in that, with the sensor module fitted on the wall, part of the cover along with part of the wall forms a further channel connecting the through-passage channel to the opening in the wall.
In accordance with a further additional feature of the invention, a printed circuit board is clamped inbetween parts of the housing and the pressure sensor, and the pressure sensor is disposed on the printed circuit board.
In accordance with a concomitant feature of the invention, a diaphragm is disposed between the through-passage channel of the sealing cushion and a surface of the pressure sensor.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a sensor module having a housing which can be fitted on a wall, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.